The purpose of the research is to investigate how communicative capacities are organized in the brain and to arrive at neurologically interpretable analyses of such capabilities. The hypothesis is that the effects of focal damage in the left and right hemispheres serves to disentangle cognitive systems that normally interact in the exercise of language-based communication. The research encompasses three levels of communication: 1) a linguistically-specific embodied as the capacity to carry out syntactic analysis; 2) a lexical-semantic component based upon a lexical inventory and upon categories of extralinguistic knowledge that serve to structure word meanings; and 3) a discourse component comprising the capacity to process meanings involved in stories, jokes, arguments, and other supra-sentential entities. The specific investigations at the syntactic level will focus on thematic and surface structure contributions to sentence processing in aphasia. These studies make use of grammatical judgments and reaction time methodologies for the assessment of comprehension as it unfolds over time. Such "on-line" methods will also be used in the studies of lexical semantics; the foci at this second level will include denotative and connotative forms of knowledge in left hemisphere damaged alphasic and right hemisphere damaged patients. Studies at the discourse level will examine the effects of right brain damage, probing the nature of limitations in integrating textual material and in comprehending no-literal forms of language. This program should yield a fuller picture of communicative capacity in aphasic and right hemisphere damaged patients, and provide a basis for implementing appropriate forms of language remediation.